1. Field of the Invention
The subject invention is directed to an implantable coronary sinus lead for left ventricular pacing and to a method of placing or otherwise implanting such a lead in the coronary sinus vein.
2. Background of the Related Art
It has been found that cardiac stimulation can have a beneficial effect in treating congestive heart failure. However, pacing therapy for treating congestive heart failure often requires left ventricular stimulation, either alone or in conjunction with right ventricular stimulation and defibrillation. Left ventricular pacing presently requires placement of an epicardial lead by way of a thoracotomy, which is a high risk procedure performed under general anesthesia.
To obviate the need for a thoracotomy, left ventricular access leads have been developed which are introduced through the coronary sinus and then advanced through the coronary veins so that the distal electrode of the lead can be positioned on the surface of the left ventricle of the heart, as disclosed for example in U.S. Pat. No. 6,711,443 to Osypka, the disclosure of which is herein incorporated by reference in its entirety.
The coronary veins of the heart are of a relatively small diameter. The pacing lead extended therethrough must therefore be of a relatively small diameter compared to pacing leads used for right ventricular stimulation. However, these leads are typically advanced into the coronary veins over guide wires or with the support of a stylet extending through a central lumen formed in the lead body. This central lumen tends to increase the overall diameter of the lead body and limits how small the lead diameter can be constructed. Furthermore, because existing leads are pushed into the coronary veins, sometimes with the support of guiding catheters, the tortuosity and stenosis in the coronary veins can impede the progress of the lead, limiting its ideal placement.
While such devices and techniques have generally been considered satisfactory for their intended purpose, there is a need in the art for smaller pacing leads and improved delivery methods.